WO2022057972A1

WO2022057972A1 - Device for honing non-round contures and method for honing a non-round raceway of a bearing ring

Info

Publication number: WO2022057972A1
Application number: PCT/DE2021/100696
Authority: WO
Inventors: Adrian HEINECKE; Werner Ohnemus
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2020-09-16
Filing date: 2021-08-16
Publication date: 2022-03-24
Also published as: DE102020124100A1

Abstract

A bearing ring having a non-circular raceway (4) for rolling elements, in particular balls, is formed by a workpiece (3). When the raceway (4) is honed, the workpiece (3), including a circular shaft portion (8) which can be either a portion of the workpiece (3) or a separate part, rotates. During the honing machining, a machining point (21) at which a honing stone (18) contacts the bearing ring (3) remains stationary, while a support point (15) at which the circular shaft portion (8) contacts a support shoe (16) oscillates in a linear direction.

Description

Device for honing non-round contours and method for honing a non-round raceway of a bearing ring

The invention relates to a device suitable for honing non-circular contours. Furthermore, the invention relates to a method for honing a non-round raceway of a bearing ring of a roller bearing.

DE 1 958 055 A discloses a honing tool for machining out-of-round bores. The well-known honing tool comprises several honing stones, which are acted upon by pistons actuated by pressure medium and is said to be suitable in particular for machining non-circular bores in the housing bodies of vane pumps.

DE 10 2012 100 503 A1 discloses a method for producing a bearing ring for a ball bearing for a servo transmission. As part of this method, a blank is clamped with a grinding mold in such a way that initially circular inner and outer surfaces of the ring-shaped blank assume a non-round shape. Then one of the two surfaces mentioned is ground round. After the blank has been removed from the grinding mold, the blank relaxes, so that the surface, which has a circular cross-section during grinding, assumes a non-round shape. Machining by honing is not discussed in DE 10 2012 100 503 A1.

An ultrasonically excited honing tool is known from EP 0 633 827 B1, which is provided for machining non-round workpieces. EP 0 633 827 B1 mentions oval bores, trochoids and internal gearing as application examples.

DE 10 2012 201 342 A1 describes a method for producing an inner surface of a bore with locally different roughness structures. A bore machined by pre-honing and finish-honing should have locally different roughness structures in different height ranges, which tion, wear and lubricant consumption are optimized. The bore is a cylinder barrel of an internal combustion engine. The method described in DE 10 2012 201 342 A1 should also be usable as a shaping method for machining non-circular bores.

Various methods for honing roller bearing rings are described, for example, in the documents DE 10 2012 204 618 A1 and DE 10 2012 221 742 A1. In the latter case, honing follows a hard turning process.

The invention is based on the object of further developing the honing of non-circular raceways of bearings compared to the prior art, the aim being particularly efficient machining with high process reliability.

This object is achieved according to the invention by a device for honing non-round contours with the features of claim 1. The object is also achieved by a method for honing a non-round raceway of a bearing ring according to claim 9. Embodiments and advantages of the invention explained below in connection with the honing method also apply to the honing device and vice versa.

The honing device designed for machining a non-circular raceway of a bearing ring or any other outer peripheral surface of a workpiece that deviates from a circular cross-section

- a receiving device rotating during operation of the honing device for receiving a workpiece, in particular a bearing ring, with an elliptical, non-circular outer peripheral surface to be machined,

- a drive device for driving the receiving device together with the workpiece,

- a shaft section with a circular contour that rotates together with the workpiece during operation of the honing device, - a first support shoe, which is provided for contacting the circular shaft section,

- a second support shoe, which is positioned in a cross-sectional area of the honing device - seen along its axis of rotation - in which a honing stone contacting the workpiece is also positioned, and on the circumference of the receiving device opposite the first support shoe by 90° ± 45°, for example by 90 ° ± 12 °, in particular by exactly 90 °, is arranged offset.

The arrangement of the second support shoe on the one hand and the honing stone on the other hand in the same cross-sectional area means that the said support shoe and the honing stone overlap in a projection representation with the projection direction parallel to the axis of rotation of the honing device. In particular, the second support shoe and the honing stone are arranged in the same peripheral area of the workpiece. In this case, the angular relation given between the two support shoes, in particular in the form of a 90° offset, also applies to the angular offset between the first support shoe and the honing stone.

According to a first possible embodiment, the shaft section with a circular contour that is supported by the first support shoe represents an integral part of the workpiece. In this case, the entire workpiece is also referred to as shaft for short. In the context of the claimed method, the circularly contoured section of the workpiece is not subjected to any honing or grinding. Of course, a honing or grinding machining or other machining of the shaft section of the workpiece having a circular contour can be carried out in a preceding or following machining step.

According to a second possible configuration, the shaft section with a circular contour is to be attributed to the receiving device. In this case, the circularly contoured shaft section can rest directly on the workpiece, that is to say the bearing ring. In this embodiment, too, a fixed geo- given metric relationship between the non-round outer peripheral surface to be machined and the circular peripheral surface of the co-rotating shaft section.

The workpiece to be machined by honing, which is, for example, a roller bearing ring, in particular a bearing inner ring, is thus supported at least indirectly and directly by the two support shoes. The indirect support - in the case of a shaft section separated from the workpiece with a circular contour - exerts a radial force on the workpiece together with the direct support. This effect can be intensified by a pressure roller and also occurs in a corresponding manner in the case of a circular shaft section formed in one piece with the workpiece.

Overall, the honing process provides a particularly stable, geometrically precise support for the workpiece. The bearing ring, which rotates together with the circular shaft section, makes contact with a honing stone, which remains stationary during honing. The stationary arrangement of the honing stone means that it does not perform any movements that are due to the non-round shape of the workpiece. Infeed or feed movements can be provided independently of this—regardless of the arrangement of the honing stone defined as stationary. The honing stone performs the oscillating movements typical of honing. When machining a grooved, non-circular raceway with the honing stone, it is not displaced in the axial direction of the workpiece. Such a displacement in the form of an oscillating axial movement can, however, be provided when machining a smooth, non-grooved roller bearing raceway. However, in this case, too, there are no oscillating movements of the honing stone in the radial direction of the workpiece.

Rather, the drive of the workpiece is designed, regardless of its geometry, in such a way that the central axis of the workpiece can be displaced in an oscillating manner relative to the central axis of the drive device, in particular a so-called driver, which loads the workpiece in the axial direction, with the amplitude and frequency of this oscillating displacement being determined by the non-circular shape of the surface to be machined by honing is specified. The deflection The central axis of the workpiece relative to the central axis of the drive device can be realized by flexibility within the drive device and/or by flexible mounting of the workpiece on the drive device, with the central axes of the drive device and workpiece always being aligned parallel to one another. One of the two support shoes or both support shoes, at least the support shoe arranged at the honing stone, tends to exert a radial force on the workpiece in the direction of an eccentric arrangement - in relation to the drive device. The workpiece-contacting back-up shoe located at the honing stone may, like the honing stone, have an elongated shape and extend parallel to the honing stone, with a gap being formed between the back-up shoe and the honing stone.

In general, the honing of an out-of-round raceway is carried out in that a processing point at which a honing stone contacts the bearing ring remains stationary during honing, whereas a support point at which a circular shaft section contacts a support shoe oscillates in a linear direction. The direction of the linear oscillation of the support point corresponds at least approximately to the direction in which the honing stone presses against the workpiece. The support shoe resting on the circular shaft section remains in the same position during the entire honing process. The width of the support shoe is greater than the difference between the semi-major axis and the semi-minor axis of the surface to be machined, provided that it has an elliptical shape, in order to allow the support point on the support shoe to move in an oscillating manner.

Both in configurations in which the circular shaft section is attributable to the receiving device and in configurations in which the circular shaft section is a section of the workpiece, in the course of the method for honing a non-circular surface, in particular a non-circular raceway of a bearing ring, the Workpiece including the circular shaft section rotated, with the circular shaft section being supported during the honing of the surface, in particular the raceway, in such a way that between a support point on the circular shaft section, the center axis of the bearing ring and an angle of 90° ± 45°, ie at least 45° and at most 135°, is included at a machining point of the honing.

Between the bearing ring or other workpiece or workpiece section on the one hand and the circular shaft section on the other hand, a non-rotatable coupling is established in all cases during honing. The non-circular raceway or other non-circular surface to be machined is located on the outer peripheral surface of the annular or tubular workpiece, in particular the bearing ring. The bearing ring can be driven with a driver known per se.

The two support shoes are offset from one another in the axial direction of the honing device according to the arrangement of the circular shaft section on the one hand and the bearing ring or other workpiece or workpiece section to be machined with a non-circular outer peripheral surface on the other hand. Here, the distance to be measured in the axial direction between the edges facing the drive device, typically lower edges, of the two support shoes can be less than the radius of the circular shaft section. The generation of tilting moments within the honing device is limited to low values due to the close arrangement of the two support shoes in relation to the radial dimensions of the circular shaft section and the workpiece in relation to the axial direction of the honing device. The cross section of the circular shaft section can lie completely within the cross section of the non-circular, elliptical track of the workpiece. In this embodiment, the non-round contour to be machined thus protrudes beyond the shaft section with a circular outer peripheral surface on the entire circumference of the workpiece.

The raceway of the bearing ring to be machined by honing can be designed in the form of grooves, so that it can be used as a ball bearing raceway. There are shoulders of the bearing ring on both sides of the raceway, with the support shoe resting against one of these shoulders. The support shoes of the honing device are made, for example, from polycrystalline diamond or from hard metal. The following options exist:

- Both support shoes, at least those surface areas that come into contact with the honing device including the workpiece, are made of polycrystalline diamond (PCD),

- the support shoe on the circular shaft section is made of polycrystalline diamond, while the support shoe on the workpiece is made of hard metal,

- the support shoe on the circular shaft section is made of hard metal, while the support shoe on the workpiece is made of polycrystalline diamond,

- Both support shoes, at least the surface areas that contact the honing device including the workpiece, are made of hard metal.

The shaft processed by honing the out-of-round ball track is particularly suitable for use in a wave generator. Reference is made to the documents DE 10 2017 119 460 B3, US 2011/0030631 A1, DE 10 2017 121 320 B3 and DE 10 2016 217 051 A1 as examples of the possible design of wave generators.

The shaft with a honed ball track can be used, among other things, in an actuating gear of a robot or a machine tool designed as a strain wave gear. Contours for positive drive of the shaft can be integrated into it.

A bearing ring machined with the honing device can be used, for example, in an actuator for adjusting an eccentric shaft within a device for varying the compression ratio of a reciprocating engine. In this context, reference is made to the documents DE 10 2018 100 905 B3 and DE 10 2018 107 058 A1 by way of example. Several exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Shown here, partly in a schematic representation:

1 shows a perspective view of a honing device,

Fig. 2 Details of the arrangement according to Figure 1 in a schematic sectional view,

3 geometric features of a workpiece and part of a receiving device of the honing device,

4 further features of the honing device in a schematic longitudinal section,

5 shows the machining of another workpiece by the honing device in a view analogous to FIG. 3,

6 shows the arrangement according to FIG. 5 with the positioning of the workpiece rotated through 90°, the central axes of the workpiece and the honing device falling apart.

Unless otherwise stated, the following explanations relate to all exemplary embodiments. Parts that correspond to one another or have the same effect in principle are identified by the same reference symbols in all figures.

A honing device, denoted overall by 1, is provided for machining a workpiece 3, which is denoted as a shaft in the first exemplary embodiment and has a section functioning as a bearing ring of a wave generator and a circular shaft section 8 adjoining it. In the exemplary embodiment according to FIGS. 5 and 6, on the other hand, the circular shaft section 8 adjusts represents a part separate from the bearing ring as workpiece 3. In both exemplary embodiments, the bearing ring, which is formed by workpiece 3 or is identical to workpiece 3, is an inner ring of a wave generator that is not shown in any more detail. The wave generator is part of a harmonic drive and is used for the permanent deformation of an elastic, externally toothed gear element during operation of the harmonic drive.

The honing device 1 comprises a receiving device 2 for receiving the workpiece 3 and a drive device 5 for driving the workpiece 3. Parts of the drive device 5 are a cylindrical rotating element 6, which is also referred to as a driver, and a conical housing part 7 in the exemplary embodiments outlined During operation of the honing device 1, the driver 6 presses directly against the workpiece 3, which has on its outer peripheral surface a non-circular, elliptical raceway 4 for rolling elements that is to be machined by honing. Within the finished wave generator, several balls roll on the raceway 4 as rolling bodies. The central axis of the drive device 5 is denoted by MH. In the exemplary embodiments, the central axis MH of the honing device is aligned vertically, with the drive device 5 being located below the workpiece 3 . The axis of symmetry of the workpiece 3 labeled MA, i.e. the central axis of the bearing ring having the non-circular raceway 4, deviates from the central axis MA depending on the angular position of the workpiece 3, as will be explained below with reference to Figures 5 and 6, but also for the first exemplary embodiment, ie the workpiece 3 designed as a wave, applies.

In both exemplary embodiments, the circular shaft section 8 is located above the raceway 5 as an integral part of the workpiece 3 (first exemplary embodiment) or as a separate annular component that can be attributed to the receiving device 2 (second exemplary embodiment). Alignments of the honing device 1 in space that deviate from this, for example with a horizontal central axis MH, are also possible. In all cases, the circular shaft section 8 and the driver 6 are located on one of the two end faces of the bearing ring 3. The radius of the circular shaft section 8 is denoted by rK. The ellipse described by the track 4 of the workpiece 3 has a large semi-axis a and a small one Semi-axis b, both semi-axes a, b are larger than the radius rK of the circular shaft section 8 in the illustrated embodiments.

In the arrangement according to FIG. Deviating from this exemplary embodiment, the shaft section 8 and the ring 9 can also be designed as a single component. In the present case, the ring 9 is pressed by two pressure rollers 10, 11, which are each mounted on a roller mount 12, in the direction of the driver 6, that is to say downwards in the present case. The ring 9 concentrically surrounds a pin 13 of the receiving device 2. The pin 13 could also be formed in one piece with the shaft section 8 and/or the ring 9. There is also the possibility of connecting the bearing ring 3, the circular shaft section 8 and the journal 13 before honing to form an inherently rigid component, which as a whole represents the workpiece 3, with the rigid connection of the individual parts 3, 8, 13, for example can be made in the form of a press bandage.

In contrast to the ring 9, the circular shaft section 8 is not only loaded in the axial direction, but is also supported in the radial direction. For this purpose, a first support shoe 16 rests against the lateral surface of the circular shaft section 8 labeled 14 , the center of the contact area between the lateral surface 14 and the first support shoe 16 being referred to as the support point 15 . In fact, it is an approximately linear support of the shaft section 8 by the first support shoe 16 . The support shoe 16 is not moved during honing.

In addition, the honing device 1 comprises a second support shoe 19 , which contacts the workpiece 3 at a shoulder, designated 20 , flanking the raceway 4 . The second support shoe 19 is arranged at a small distance below a honing stone 18 with which the honing of the groove-shaped raceway 4 is carried out. An edit point, that is, the center of the contact area between the honing stone 18 and the track 4 is denoted by 21. An approximately right angle is enclosed between the machining point 21, the central axis MA of the workpiece 3 and the support point 15, with slight deviations from the right angle due to relative movements occurring during honing, in particular oscillations, being disregarded.

The support point 15 is offset somewhat in relation to the processing point 21 in the axial direction, that is to say in the longitudinal direction of the central axes MA, MH. The edge of the first support shoe 16, labeled 22, facing the workpiece 3, represents the lower edge of the first support shoe 16 in the orientation of the honing device 1 selected in the exemplary embodiments. Similarly, an edge of the second support shoe, labeled 23, facing the drive device 5 19 represents its lower edge. The distance between the two lower edges 22, 23 is denoted by DS and is less than the radius rK of the circular shaft section 8.

FIGS. 5 and 6 illustrate the migration of the support point 15 on the first support shoe 16. In the positioning according to FIG. 5, the direction in which the honing stone 18 presses against the raceway 4 corresponds to the alignment of the semi-minor axis b. In this case, the central axes MA, MH coincide; the distance between the central axis MA and the second support shoe 19 is minimal. The direction in which the honing stone 18 presses against the workpiece 3 and in which the workpiece 3 is supported by the second support shoe 19 is referred to as the x-direction. The z-direction is the direction in which the workpiece is supported by the first support shoe 16 .

If the workpiece 3 is rotated further by 90° in relation to the arrangement according to FIG. 5, resulting in the positioning according to FIG. 6, then the large semi-axis a is aligned in the x-direction. The central axis MA of the workpiece 3 is displaced relative to the central axis MH in accordance with the difference between the two semi-axes a, b, this displacement being expressed 1:1 in a displacement of the support point 15 on the first support shoe 15 . The distance of the central axis MA from the first support shoe 16 measured in the z-direction remains the same in this case. The ones shown in Figures 5 6 and 6 exaggerated parallel displacements between the central axes MA, MH are absorbed by the honing device 1. The support point 15 can thus perform a linear oscillating movement during honing, the amplitude of which corresponds to the difference between the two semi-axes a, b, while the positions of the support shoes 15, 19 remain constant.

Reference character list

1 honing device

2 recording device

3 workpiece

4 elliptical track

5 drive device

6 cylindrical rotating element, driver

7 housing part

8 circular wave section

9 rings

10 pinch roller

11 pinch roller

12 roll holder

13 cones

14 Lateral surface of the circular shaft section

15 support point on the circular shaft section

16 first support shoe contacting the circular shaft portion

17 support shoe holder

18 honing stone

19 second support shoe contacting the bearing ring at the shoulder

20 shoulder

21 edit point

22 Lower edge of the first support shoe

23 Lower edge of the second support shoe a large semi-axis b small semi-axis

DS Distance between the bottom edges of the support shoes

MA Central axis of the workpiece

MH central axis of the driving device of the honing device rK radius of the circular shaft section

Claims

Claims Device for honing non-round contours, comprising

- a rotatable recording device

(2) to pick up a workpiece

(3) having an elliptical, non-circular outer peripheral surface to be machined

(4),

- a drive device (5) for driving the receiving device (2) together with the workpiece (3),

- a shaft section (8) with a circular contour that can be rotated with the workpiece (3),

- a first support shoe (16), which is provided for contacting the circular shaft section (8),

- a second support shoe (19), which is positioned in a cross-sectional area of the honing device - seen along its axis of rotation (AH) - in which a honing stone (18) contacting the workpiece (3) is also positioned, and on the periphery of the receiving device ( 2) is offset from the first support shoe (16) by 90° ± 45°. Device according to Claim 1, characterized in that the second support shoe (19) is arranged offset by 90° on the circumference of the receiving device (2) relative to the first support shoe (16). Device according to Claim 1 or 2, characterized in that the shaft section (8) with a circular contour is part of the workpiece (3). Device according to Claim 1 or 2, characterized in that the shaft section (8) with a circular contour is formed by the receiving device (2). Device according to one of claims 1 to 4, characterized in that the drive device

(5) comprises a driver (6) loading the receiving device (2) together with the workpiece (3) in the axial direction, the central axis (MA) of the workpiece (3) being displaceable relative to the central axis (MH) of the driver (6).

6. Device according to one of claims 1 to 5, characterized in that the distance (DS) to be measured in the axial direction of the receiving device (2) between the lower edges (22, 23) of the two support shoes (16, 19) is less than the radius ( rK) of the circular shaft section (8).

7. Device according to one of claims 1 to 6, characterized in that at least one of the support shoes (16, 19) comprises polycrystalline diamond.

8. Device according to one of claims 1 to 7, characterized in that at least one of the support shoes (16, 19) has hard metal.

9. Method for honing a non-circular raceway (4) of a bearing ring (3) rotating together with a circular shaft section (8), wherein during honing a processing point (21) at which a honing stone (18) contacts the bearing ring (3), remains stationary, whereas a support point (15) at which the circular shaft section (8) contacts a support shoe (16) oscillates in a linear direction.

10. The method according to claim 9, characterized in that the bearing (3) is supported in the radial direction during the honing with a further support shoe (19) extending parallel to the honing stone (18).